1 /* 2 * Copyright (c) 2015 Marko Kreen <markokr@gmail.com> 3 * Copyright (c) 2016 Bob Beck <beck@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <sys/types.h> 19 20 #include <arpa/inet.h> 21 #include <netinet/in.h> 22 23 #include <openssl/err.h> 24 #include <openssl/ocsp.h> 25 #include <openssl/x509.h> 26 27 #include <tls.h> 28 #include "tls_internal.h" 29 30 #define MAXAGE_SEC (14*24*60*60) 31 #define JITTER_SEC (60) 32 33 /* 34 * State for request. 35 */ 36 37 static struct tls_ocsp * 38 tls_ocsp_new(void) 39 { 40 return (calloc(1, sizeof(struct tls_ocsp))); 41 } 42 43 void 44 tls_ocsp_free(struct tls_ocsp *ocsp) 45 { 46 if (ocsp == NULL) 47 return; 48 49 free(ocsp->ocsp_result); 50 ocsp->ocsp_result = NULL; 51 free(ocsp->ocsp_url); 52 ocsp->ocsp_url = NULL; 53 free(ocsp); 54 } 55 56 static int 57 tls_ocsp_asn1_parse_time(struct tls *ctx, ASN1_GENERALIZEDTIME *gt, time_t *gt_time) 58 { 59 struct tm tm; 60 61 if (gt == NULL) 62 return -1; 63 /* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */ 64 if (ASN1_time_parse(gt->data, gt->length, &tm, 65 V_ASN1_GENERALIZEDTIME) == -1) 66 return -1; 67 if ((*gt_time = timegm(&tm)) == -1) 68 return -1; 69 return 0; 70 } 71 72 static int 73 tls_ocsp_fill_info(struct tls *ctx, int response_status, int cert_status, 74 int crl_reason, ASN1_GENERALIZEDTIME *revtime, 75 ASN1_GENERALIZEDTIME *thisupd, ASN1_GENERALIZEDTIME *nextupd) 76 { 77 struct tls_ocsp_result *info = NULL; 78 79 free(ctx->ocsp->ocsp_result); 80 ctx->ocsp->ocsp_result = NULL; 81 82 if ((info = calloc(1, sizeof (struct tls_ocsp_result))) == NULL) { 83 tls_set_error(ctx, "calloc"); 84 return -1; 85 } 86 info->response_status = response_status; 87 info->cert_status = cert_status; 88 info->crl_reason = crl_reason; 89 if (info->response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 90 info->result_msg = 91 OCSP_response_status_str(info->response_status); 92 } else if (info->cert_status != V_OCSP_CERTSTATUS_REVOKED) { 93 info->result_msg = OCSP_cert_status_str(info->cert_status); 94 } else { 95 info->result_msg = OCSP_crl_reason_str(info->crl_reason); 96 } 97 info->revocation_time = info->this_update = info->next_update = -1; 98 if (revtime != NULL && 99 tls_ocsp_asn1_parse_time(ctx, revtime, &info->revocation_time) != 0) { 100 tls_set_error(ctx, 101 "unable to parse revocation time in OCSP reply"); 102 goto error; 103 } 104 if (thisupd != NULL && 105 tls_ocsp_asn1_parse_time(ctx, thisupd, &info->this_update) != 0) { 106 tls_set_error(ctx, 107 "unable to parse this update time in OCSP reply"); 108 goto error; 109 } 110 if (nextupd != NULL && 111 tls_ocsp_asn1_parse_time(ctx, nextupd, &info->next_update) != 0) { 112 tls_set_error(ctx, 113 "unable to parse next update time in OCSP reply"); 114 goto error; 115 } 116 ctx->ocsp->ocsp_result = info; 117 return 0; 118 error: 119 free(info); 120 return -1; 121 } 122 123 static OCSP_CERTID * 124 tls_ocsp_get_certid(X509 *main_cert, STACK_OF(X509) *extra_certs, 125 SSL_CTX *ssl_ctx) 126 { 127 X509_NAME *issuer_name; 128 X509 *issuer; 129 X509_STORE_CTX storectx; 130 X509_OBJECT tmpobj; 131 OCSP_CERTID *cid = NULL; 132 X509_STORE *store; 133 134 if ((issuer_name = X509_get_issuer_name(main_cert)) == NULL) 135 return NULL; 136 137 if (extra_certs != NULL) { 138 issuer = X509_find_by_subject(extra_certs, issuer_name); 139 if (issuer != NULL) 140 return OCSP_cert_to_id(NULL, main_cert, issuer); 141 } 142 143 if ((store = SSL_CTX_get_cert_store(ssl_ctx)) == NULL) 144 return NULL; 145 if (X509_STORE_CTX_init(&storectx, store, main_cert, extra_certs) != 1) 146 return NULL; 147 if (X509_STORE_get_by_subject(&storectx, X509_LU_X509, issuer_name, 148 &tmpobj) == 1) { 149 cid = OCSP_cert_to_id(NULL, main_cert, tmpobj.data.x509); 150 X509_OBJECT_free_contents(&tmpobj); 151 } 152 X509_STORE_CTX_cleanup(&storectx); 153 return cid; 154 } 155 156 struct tls_ocsp * 157 tls_ocsp_setup_from_peer(struct tls *ctx) 158 { 159 struct tls_ocsp *ocsp = NULL; 160 STACK_OF(OPENSSL_STRING) *ocsp_urls = NULL; 161 162 if ((ocsp = tls_ocsp_new()) == NULL) 163 goto failed; 164 165 /* steal state from ctx struct */ 166 ocsp->main_cert = SSL_get_peer_certificate(ctx->ssl_conn); 167 ocsp->extra_certs = SSL_get_peer_cert_chain(ctx->ssl_conn); 168 if (ocsp->main_cert == NULL) { 169 tls_set_errorx(ctx, "no peer certificate for OCSP"); 170 goto failed; 171 } 172 173 ocsp_urls = X509_get1_ocsp(ocsp->main_cert); 174 if (ocsp_urls == NULL) 175 goto failed; 176 ocsp->ocsp_url = strdup(sk_OPENSSL_STRING_value(ocsp_urls, 0)); 177 if (ocsp->ocsp_url == NULL) { 178 tls_set_errorx(ctx, "out of memory"); 179 goto failed; 180 } 181 182 X509_email_free(ocsp_urls); 183 return ocsp; 184 185 failed: 186 tls_ocsp_free(ocsp); 187 X509_email_free(ocsp_urls); 188 return NULL; 189 } 190 191 static int 192 tls_ocsp_verify_response(struct tls *ctx, OCSP_RESPONSE *resp) 193 { 194 OCSP_BASICRESP *br = NULL; 195 ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL; 196 OCSP_CERTID *cid = NULL; 197 STACK_OF(X509) *combined = NULL; 198 int response_status=0, cert_status=0, crl_reason=0; 199 int ret = -1; 200 unsigned long flags; 201 202 if ((br = OCSP_response_get1_basic(resp)) == NULL) { 203 tls_set_errorx(ctx, "cannot load ocsp reply"); 204 goto error; 205 } 206 207 /* 208 * Skip validation of 'extra_certs' as this should be done 209 * already as part of main handshake. 210 */ 211 flags = OCSP_TRUSTOTHER; 212 213 /* now verify */ 214 if (OCSP_basic_verify(br, ctx->ocsp->extra_certs, 215 SSL_CTX_get_cert_store(ctx->ssl_ctx), flags) != 1) { 216 tls_set_error(ctx, "ocsp verify failed"); 217 goto error; 218 } 219 220 /* signature OK, look inside */ 221 response_status = OCSP_response_status(resp); 222 if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) { 223 tls_set_errorx(ctx, "ocsp verify failed: response - %s", 224 OCSP_response_status_str(response_status)); 225 goto error; 226 } 227 228 cid = tls_ocsp_get_certid(ctx->ocsp->main_cert, 229 ctx->ocsp->extra_certs, ctx->ssl_ctx); 230 if (cid == NULL) { 231 tls_set_errorx(ctx, "ocsp verify failed: no issuer cert"); 232 goto error; 233 } 234 235 if (OCSP_resp_find_status(br, cid, &cert_status, &crl_reason, 236 &revtime, &thisupd, &nextupd) != 1) { 237 tls_set_errorx(ctx, "ocsp verify failed: no result for cert"); 238 goto error; 239 } 240 241 if (OCSP_check_validity(thisupd, nextupd, JITTER_SEC, 242 MAXAGE_SEC) != 1) { 243 tls_set_errorx(ctx, 244 "ocsp verify failed: ocsp response not current"); 245 goto error; 246 } 247 248 if (tls_ocsp_fill_info(ctx, response_status, cert_status, 249 crl_reason, revtime, thisupd, nextupd) != 0) 250 goto error; 251 252 /* finally can look at status */ 253 if (cert_status != V_OCSP_CERTSTATUS_GOOD && cert_status != 254 V_OCSP_CERTSTATUS_UNKNOWN) { 255 tls_set_errorx(ctx, "ocsp verify failed: revoked cert - %s", 256 OCSP_crl_reason_str(crl_reason)); 257 goto error; 258 } 259 ret = 0; 260 261 error: 262 sk_X509_free(combined); 263 OCSP_CERTID_free(cid); 264 OCSP_BASICRESP_free(br); 265 return ret; 266 } 267 268 /* 269 * Process a raw OCSP response from an OCSP server request. 270 * OCSP details can then be retrieved with tls_peer_ocsp_* functions. 271 * returns 0 if certificate ok, -1 otherwise. 272 */ 273 static int 274 tls_ocsp_process_response_internal(struct tls *ctx, const unsigned char *response, 275 size_t size) 276 { 277 int ret; 278 OCSP_RESPONSE *resp; 279 280 resp = d2i_OCSP_RESPONSE(NULL, &response, size); 281 if (resp == NULL) { 282 tls_ocsp_free(ctx->ocsp); 283 ctx->ocsp = NULL; 284 tls_set_error(ctx, "unable to parse OCSP response"); 285 return -1; 286 } 287 ret = tls_ocsp_verify_response(ctx, resp); 288 OCSP_RESPONSE_free(resp); 289 return ret; 290 } 291 292 /* TLS handshake verification callback for stapled requests */ 293 int 294 tls_ocsp_verify_cb(SSL *ssl, void *arg) 295 { 296 const unsigned char *raw = NULL; 297 int size, res = -1; 298 struct tls *ctx; 299 300 if ((ctx = SSL_get_app_data(ssl)) == NULL) 301 return -1; 302 303 size = SSL_get_tlsext_status_ocsp_resp(ssl, &raw); 304 if (size <= 0) { 305 if (ctx->config->ocsp_require_stapling) { 306 tls_set_errorx(ctx, "no stapled OCSP response provided"); 307 return 0; 308 } 309 return 1; 310 } 311 312 tls_ocsp_free(ctx->ocsp); 313 ctx->ocsp = tls_ocsp_setup_from_peer(ctx); 314 if (ctx->ocsp != NULL) { 315 if (ctx->config->verify_cert == 0 || ctx->config->verify_time == 0) 316 return 1; 317 res = tls_ocsp_process_response_internal(ctx, raw, size); 318 } 319 320 return (res == 0) ? 1 : 0; 321 } 322 323 324 /* Staple the OCSP information in ctx->ocsp to the server handshake. */ 325 int 326 tls_ocsp_stapling_cb(SSL *ssl, void *arg) 327 { 328 struct tls *ctx; 329 unsigned char *ocsp_staple = NULL; 330 int ret = SSL_TLSEXT_ERR_ALERT_FATAL; 331 332 if ((ctx = SSL_get_app_data(ssl)) == NULL) 333 goto err; 334 335 if (ctx->config->ocsp_staple == NULL || 336 ctx->config->ocsp_staple_len == 0) 337 return SSL_TLSEXT_ERR_NOACK; 338 339 if ((ocsp_staple = malloc(ctx->config->ocsp_staple_len)) == NULL) 340 goto err; 341 342 memcpy(ocsp_staple, ctx->config->ocsp_staple, 343 ctx->config->ocsp_staple_len); 344 if (SSL_set_tlsext_status_ocsp_resp(ctx->ssl_conn, ocsp_staple, 345 ctx->config->ocsp_staple_len) != 1) 346 goto err; 347 348 ret = SSL_TLSEXT_ERR_OK; 349 err: 350 if (ret != SSL_TLSEXT_ERR_OK) 351 free(ocsp_staple); 352 return ret; 353 } 354 355 /* 356 * Public API 357 */ 358 359 /* Retrieve OSCP URL from peer certificate, if present */ 360 const char * 361 tls_peer_ocsp_url(struct tls *ctx) 362 { 363 if (ctx->ocsp == NULL) 364 return NULL; 365 return ctx->ocsp->ocsp_url; 366 } 367 368 const char * 369 tls_peer_ocsp_result(struct tls *ctx) 370 { 371 if (ctx->ocsp == NULL) 372 return NULL; 373 if (ctx->ocsp->ocsp_result == NULL) 374 return NULL; 375 return ctx->ocsp->ocsp_result->result_msg; 376 } 377 378 int 379 tls_peer_ocsp_response_status(struct tls *ctx) 380 { 381 if (ctx->ocsp == NULL) 382 return -1; 383 if (ctx->ocsp->ocsp_result == NULL) 384 return -1; 385 return ctx->ocsp->ocsp_result->response_status; 386 } 387 388 int 389 tls_peer_ocsp_cert_status(struct tls *ctx) 390 { 391 if (ctx->ocsp == NULL) 392 return -1; 393 if (ctx->ocsp->ocsp_result == NULL) 394 return -1; 395 return ctx->ocsp->ocsp_result->cert_status; 396 } 397 398 int 399 tls_peer_ocsp_crl_reason(struct tls *ctx) 400 { 401 if (ctx->ocsp == NULL) 402 return -1; 403 if (ctx->ocsp->ocsp_result == NULL) 404 return -1; 405 return ctx->ocsp->ocsp_result->crl_reason; 406 } 407 408 time_t 409 tls_peer_ocsp_this_update(struct tls *ctx) 410 { 411 if (ctx->ocsp == NULL) 412 return -1; 413 if (ctx->ocsp->ocsp_result == NULL) 414 return -1; 415 return ctx->ocsp->ocsp_result->this_update; 416 } 417 418 time_t 419 tls_peer_ocsp_next_update(struct tls *ctx) 420 { 421 if (ctx->ocsp == NULL) 422 return -1; 423 if (ctx->ocsp->ocsp_result == NULL) 424 return -1; 425 return ctx->ocsp->ocsp_result->next_update; 426 } 427 428 time_t 429 tls_peer_ocsp_revocation_time(struct tls *ctx) 430 { 431 if (ctx->ocsp == NULL) 432 return -1; 433 if (ctx->ocsp->ocsp_result == NULL) 434 return -1; 435 return ctx->ocsp->ocsp_result->revocation_time; 436 } 437 438 int 439 tls_ocsp_process_response(struct tls *ctx, const unsigned char *response, 440 size_t size) 441 { 442 if ((ctx->state & TLS_HANDSHAKE_COMPLETE) == 0) 443 return -1; 444 return tls_ocsp_process_response_internal(ctx, response, size); 445 } 446